TABLES OF CONSTANTS OF NATURE AND ART. 291 



when under different modes of cultivation ; hay, straw, wheat, tur- 

 nips, and mangel wurzel, potatoes, clover ; etc. produce of timber 

 per acre. 



10. Tables of the geographical distribution of animals and of plants ; 

 of the average period of maturity and decay in various woods ; increase 

 in weight annually at different periods ; weight of potass produced 

 from earth ; proportion of heat produced by burning given weight. 



11. Atmospheric phenomena. Weight of air above a square inch; 

 square foot ; an acre ; a square mile of the earth's surface, barometer 

 at 30 inches. Weight of oxygen, of nitrogen^ of carbonic acid, above 

 the same spaces, under the same circumstances. 



Weight of water in vapor above ditto at various degrees of hy- 

 grometer. Depth of rain falling annually at various places, in inches, 

 columns for number of year's observation, mean temperature, mean 

 height of barometer, height of places above the sea ; drainage of sur- 

 face-water for one, two, three, to ten inches, from each square of 100 

 feet side, each acre, or square mile, expressed in cubic feet, in gallons, 

 and in hogsheads ; water discharged per" or 1', per hour or per day^ 

 under various circumstances, as found by experiment; velocity of rivers 

 and torrents to carry stones of given weight. 



12. Materials. Height to which a column of any substance used in 

 building may be carried before the lowest layer is crushed ; weight 

 necessary to crush a cubic inch of each ; weight of cubic foot or cubic 

 yard. Angles at which sand, gravel of various sized pebbles, snow, 

 etc., support themselves. Strength necessary to pull asunder various 

 woods ; bars of metal of various dimensions ; weight to break ropes 

 and chains of various sizes ; column for weight to be safely borne by 

 them ; friction under various circumstances ; resistance of fluids. 



Weight of coal to burn 10 bushels of lime ; weight of ashes to burn 

 10,000 brick ; of coke to make ton of wrought-iron ; tallow to make 

 soap, etc. ; and constants in all trades. 



See Rennie, Tredgold, Prony, Eytelwein, Yenturi, etc. 



13. Velocities. Arrow, musket ball at several distances, cannon ball, 

 sound, telegraph, light, birds. 



Day'sjourney. Man, horse, heavy wagon, stage-coach, mail-coach, 

 camel, elephant, steam carriage, steamboat, balloon, greatest; average 

 passage Liverpool to New York, etc., of steamboats, Dublin to Liver- 

 pool ; London to Edinburgh, etc. 



14. Length of all rivers ; water discharged Y>ev hour ; seas ; pro- 

 portion of water to land on globe ; area of all seas and lakes in square 

 miles ; areas of all island's and peninsula and continents ; heights of 

 mountains ; depth of mines from surface ; quantity of water 

 pumped out of mines. 



Heights of above 7,000 points in Europe may be found in OrograpJiie, 

 the third volume of the Transactions of the Geographical Society of 

 Paris. 



15. Poi^ulation, extent in square miles, revenue, etc., of kingdoms; 

 births, deaths, marriages, rate of increase, population of great towns. 



